The form factor of a mobile phone is its size, shape, and style, as well as the layout and position of its major components. There are three major form factors—bar phones, flip phones, and sliders—as well as sub-categories of these forms and some atypical forms. The most common form factor in mobile phones today is a slate or touchscreen phone which is a subset of the bar form. The bar form, like a tablet computer, has few physical buttons, instead relying upon a touchscreen and an onscreen keyboard. Since the mid-2010s, almost all smartphones come in a “touchscreen” slate form.